Surface energies and size-effects in shape-memory-alloys

We investigate the dependence of the austenite-to-martensite phase-transformation temperature on the surface energy present in the interfaces between different martensite variants. Our approach is based on the observation that the material has to produce volumetric elastic strain in order to accomodate spatially varying lath width in martensitic twin microstructures. Minimization of total energy then yields spatial distributions of volumetric and surface energies from which the transformation temperature can be calculated. An application to particle growth within a shape-memory-alloy matrix is given.